18 month-old female cattle Yoriko, from Kagoshima prefecture, is posed for a photograph during a photo session after winning the breeding cattle category - young female cattle division competition at 11th National Japanese Beef Ability Expo, commonly known as Wagyu Olympics, in Sendai, northern Japan September 10, 2017. Picture taken September 10, 2017. REUTERS/Issei Kato

SENDAI, Japan (Reuters) - More than 500 cattle paraded through a ring in northern Japan in the “Wagyu Olympics” to win prizes and renown as the most fertile - and mouth-watering - examples of “wagyu” beef, increasingly popular among foodies around the world.

The six-day contest that ended in Miyagi prefecture on Monday saw breeders of wagyu, prized by gourmet fans for its luscious marbling, compete for fame in categories such as best beef cattle, best bull and most fertile cow.

“I really can’t believe it, I‘m so happy,” said 69-year-old Tadanao Sato, who claimed a trophy and bragging rights for nurturing Fumiayame, who won top prize for her beauty and high fertility.

Fertility is judged by the shape of the cow’s shoulders, its toned legs, and the “topline”, or the flatness of the back.

Beef quality is judged by the cattle’s fat marbling and leanness.

Overseas demand for wagyu, which means “Japanese beef”, has soared since widespread import bans were lifted more than a decade after an outbreak of mad cow disease in 2001.

Breeders, supporters and officials from Kagoshima prefecture celebrate after winning a division of breeding cattle category competition at 11th National Japanese Beef Ability Expo, commonly known as Wagyu Olympics, in Sendai, northern Japan September 10, 2017. Picture taken September 10, 2017. REUTERS/Issei Kato

In 2016, beef was Japan’s top export in the agricultural and livestock category, raking in 13.6 billion yen ($125 million).

“These last few years, the boom in Japanese food, as well as widespread praise for the high quality of wagyu, have caused overseas demand to grow rapidly,” said Toru Takano, an official of the National Federation of Agricultural Co-operative Associations.

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“We have been, and will try bit by bit, to open up wagyu markets overseas.”

Though “seed cattle” winners at the five-yearly event, such as Fumiayame, go home to be cosseted and produce future generations of winners, the beef division winners are slaughtered the day after the judging and are promptly frozen and auctioned at the Olympics.

The most expensive beef went for 54,001 yen ($498) per kilo, and the most moderate for 3,241 yen.